1. Field of the Invention
This invention relates in general to model railroad switch machines and more particularly to a model railroad switch machine having a single wire control input, user programmable synchronization of indicator lights, realistic slow speed switching action simulating the operation of full size railroad switches and self calibration for enhancing realism as switch mechanical resistance and voltage changes are encountered.
2. Description of Related Art
Known switch machines or switch actuators for model railroad applications take a variety of forms. Solenoids are commonly used to actuate the switches because they are small and efficient and can provide relatively high power. One problem with solenoid actuators is that they produce a snap action that is effective for moving the switch but which is not very realistic. Switch machines for actual locomotives use relatively large, slow moving motors and changing the position of a switch typically takes several seconds. It is desirable for enhancing realism to provide a switch machine for a model railroad layout that also moves the switch slowly to more accurately simulate a real switch.
Switch machines have been proposed that employ a rack and pinion assembly connected to a small motor for driving the switch. While these have the ability to provide a realistic switching speed, they add a level of complexity. The motor must be driven in one direction to move the switch one way and reverse to move the switch the other way. This adds complexity and cost to the controller and multiplies the number of wires that must be run to the switch machine. It is desirable to have a switch machine that uses the minimum possible number of control wires.
Model train switching machines frequently include signals, most often light signals, for indicating the position of the switch. Such light signals are important because the position of the switch is often difficult to see directly and a miss positioned switch could cause a derailment. While signal lights are known for use in model railroad switching machines, a problem not so far addressed is the problem of synchronizing the lights with the position of the switch especially when the model railroad switch machine is responsive to a switching signal to switch from whatever state it is presently in to the other state. A known solution to this problem is to make the lights, most often red and green lights, removable so that the lights can be removed and reinstalled such that the green light indicates that the switch is in the through position while the red light indicates that the switch is in the out position. It is desirable to provide a switch that can be synchronized without removing the lights and permitting the switch machine to be mounted on either side of the switch.